Conventions Used in This Book

The following programming and typesetting conventions are used in this book.

Programming Conventions

The <?php and ?> opening and closing markers that begin and end a PHP program are generally omitted from examples in this book, except in examples where the body of the code includes an opening or closing marker.

The examples in this book were written to run under PHP 5 on both Unix and Windows, except where noted in the text.

At the time this book went to press, the latest available version of PHP 5 was Release Candidate 3 (RC3). Also, MySQL 4.1 was in beta. It is possible that some changes may occur between RC3 and the final release. Please check the online errata at for any last-minute updates.

Typesetting Conventions

The following typographical conventions are used in this book:


Indicates new terms, URLs, email addresses, filenames, file extensions, pathnames, and directories.

Constant width

Indicates commands, options, switches, variables, attributes, keys, functions, types, classes, namespaces, methods, modules, properties, parameters, values, objects, events, event handlers, XML tags, HTML tags, macros, the contents of files, or the output from commands.

Constant Width Bold

Indicates the output from code examples.

Constant width italic

Shows text that should be replaced with user-supplied values.

This icon signifies a tip, suggestion, or general note.

This icon indicates a warning or caution.